This invention relates to a multi-processor system, and more specifically to a multi-processor system capable of exercising smooth job swapping control from a higher priority processor unit to a lower priority processor unit.
The multi-processor system is available for improving system efficiency by employing a plurality of processor units. In parallel processing of programs by the system, each job step of the program to be processed is divided into tasks, and an input-output device is allocated by means of an operating system. In doing this, a dynamic programming method is used, allocating an area of the main memory for each task and controlling the scheduling of input-output operations through a supervisory program. In a multi-processor system, however, when the processor units are subject to interruption of service due to a request for other job services higher in priority while one processor unit is performing a job service, the job service presently in process may be abandoned. There may also be required a job sequence in which where as in the case of time-sharing, the interruption timing is regulated by the operating system, the job in process is stopped for a predetermined time while, job services higher in priority are performed and then the job in question is resumed.